This invention relates to machinery for the assembly of upholstery spring coils into "constructions," so-called, which become the cores of mattresses or cushions.
More particularly, it relates to improvements in mechanism for transferring upholstery spring coils, a row at a time, from a feeding station to a delivery station, usually the input end of an automatic assembly machine such as that illustrated in Woller U.S. Pat. No. 2,388,100, or the assembly machines manufactured by Wells, Woodfield, or Spuhl.
The transfer mechanism of the invention is particularly suited to the fully automated assembly of spring coil constructions, i.e., one in which the assembly begins with a coil feeder such as the feeder of my U.S. Pat. No. 3,193,136, capable of isolating a row of individual spring coils from a bulk supply of coils in nested stacks for subsequent delivery by the transfer mechanism directly into the jaws or other receiving station of the assembly machine.
In such an automated repetitive operation, the production rate is governed by the cycling time of the slowest constituent part, which, in the case of a system including the three principal elements of feeder, transfer mechanism, and assembly machine, has, in my experience, been the transfer mechanism, particularly when the assembly machine cycle is foreshortened for twin size and other narrow constructions.
It is accordingly the object of my improved transfer mechanism to reduce the period of its operating cycle by an economy of movement of the operating parts to achieve a faster yet smoother and more vibration-free movement than marked the operation of earlier mechanisms for this purpose. In particular, the transfer of spring coils, a row at a time, from the coil feeder into the assembly machine involves the movement of the coils across the substantial intervening distance which is maintained to provide access for maintenance of, and for the clearing of occasional operational difficulties in, the assembly machine. The actual transfer of coils is preceded by the extraction of the spring coils from the feeder by the transfer mechanism at the initiation of the transfer movement, and completed by their forcible insertion by the transfer mechanism into the assembly machine, the spring coils being turned end for end by a half-rotation which carries them from a trailing position at the rear of the transfer mechanism to an advancing front position during the delivery movement of the transfer mechanism. In the known mechanisms which employ the overturning movement of the coils through a half-revolution on the forward movement of the transfer mechanism, the transfer mechanism likewise rotates a reciprocal half-turn in the reverse direction during the return movement to reposition the coil gripping mechanisms anew at the feeding station for the beginning of the next cycle.
As will become apparent from the following description, my improved transfer mechanism eliminates the need for a resetting movement on the return travel of the transfer mechanism by employing a second and opposed set of coil grippers which are already positioned for a new cycle by the half-rotation of the coils on the forward delivery motion of the transfer mechanism, and, accordingly, eliminates the need for that energy and time-consuming resetting movement on the return movement of the transfer mechanism to the feeder.